How to fix 17887/P1479 brake boost vacuum and 18033/P1625 powertrain data bus?

Told you already. The data bus goes between all the computers in the vehicle. All of them. Do Not apply 12 volt power to them.

code p 1625 refers to CAN databus, TCM--incorrect signal===causes --TCM trouble code/s stored---TCM incorrectly coded---wiring---matching resistor in ECM
I don't have a listing for code p 1749 but codes 1748 and 1750 are concerned with TCM defective and voltage supply low
so after you check the wiring and connections form the transmission you have 2 options
use a known good ECM to replace yours ( will eliminate any ECM faults)
and/or replace the TCM module on the transmission

Hey John ! how's it going ? How do you know you have a class 2 data bus problem ? Need some more info ! Do you have a scan tool ? Can't communicate with the PCM ? Have a check engine light on ?
You may access 2 data lines with the scan tool. The serial data line UART (circuit 800) allows the following components to communicate via serial data:
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The scan tool

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The powertrain control module (PCM)

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The instrument panel cluster

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The sensing diagnostic module (SDM)

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The electronic brake control module (EBCM)

The serial data line class 2 (circuit 1807) allows the scan tool to access directly the PCM in order to read emissions-related information. The scan tool gains access to both data lines through the data link connector (DLC). You may then monitor or control system operations for diagnostic purposes.

if you can read the faults then teh code reader should tell you ,if not then download OBDII codes from a torrent site as iam feeding .


P1479 Vacuum system, brakes - mechanical fault
P1403 EGR Flow Deviation

3089 is not showing in my VW code sheet

Here try this solution...You posted P1479. ...When this fault is stored in conjunction with misfire and system lean fault codes check the PCV system and any other possible sources of engine mechanical vacuum leaks. Although PCV failure is most common on the 1.8T engines equipped with the auxiliary vacuum pump, any engine with low vacuum can cause that electric pump to run excessively - resulting in this fault code. Good luck.

P1625 means that the engine computer has lost communication with the antilock brake and/or traction control computer for at least 3 seconds. How expensive this is depends on why it has lost communication, It could be something as simple as a loose connection at a wiring connector or a broken or shorted wire in the PCI bus circuit inside the wiring harness. (Which may require considerable diagnostic time to find) or it could be an internally failed ABS module.

Recommendation:
If you are NOT experiencing ANY of the symptoms below, I would simply clear the code and move on.... It is an intermittent fault that you will most likely not find very easily. If you ARE experiencing ONE OR MORE of these symptoms, then the problem needs to be diagnosed by checking the ABS module's ability to communicate with a scanner while testing the PCI Bus circuits.

Other possible symptoms of Diagnostic Trouble Code (DTC) P1625
• Speedometer malfunctioning
• Traction Control malfunctioning
• Antilock Brake System malfunctioning or ABS light on
• Cruise Control malfunctioning

Yes If you have a vacuum leak it will pop the oxygen sensor codes to rich/ to lean. the rpm code is some thing different, it could be as simple as you over revving the car.

The P1698 code means that no digital data is being received by the powertrain controller from the transmission control module, located on the right inner fender. The manual says to check the CCD bus wires between the module and the rest of the system using the Chrysler diagnostic readout box. But if you don't have one then I think you can do the same thing by measuring for continuity (near 0 resistance) between pin 4 of its plug and pin 11 of the data link plug under the dash or pin 59 of the powertrain controller plug.
Then check the resistance between pin 43 if its plug and pin 3 of the data link connector or pin 60 of the powertrain controller plug. The powertrain controller is on the opposite side of the engine compartment on the left inner fender. These module plugs are held in place by a bolt. If the continuity between the transmission and the powertrain CCD wires checks to be ok, then according to the manual the trans controller should be replaced.
That is my analysis of what you report. You may have been told to replace the body control module erroneously because the code for that is P1695. If the independent garage was using the check engine light as its diagnostic methodology those problems both give a code 66, so they may guessed that it was the body module as being the faulty one. Problems with starting and with gauges are often related to this data bus communication system so all your issues seem to point this way. You might also, when checking the wires, also verify that they are not shorted to ground.